I am going to interface a RTC to PIC18F and before doing so, I'd like to clear some doubts regarding the module and its connections. I am using the "Tiny RTC" as shown in this link!.

The following questions are:

  1. What is the use of the SRAM in the RTC chip? From my findings, I got to know that the SRAM is used to store the current time and date when the chip is powered off while being backed up by the battery to keep the time. Is this right?, If so, does the data backing up happen internally?

  2. What is the use of the onboard AT24C32N EEPROM?. Does it have to do anything with the RTC chip?

  3. I am not using the LIR2032 rechargeable battery but using the normal CR2032 non rechargeable battery. From this video link!, It is suggested to remove some components to prevent the CR2032 from being charged as it will cause overheating to damaging it. Just to confirm,Is this necessary?

  4. Now coming to the module connections. How do I know If the +ve terminal of the CR2032 is connected to VBAT terminal of the RTC chip and its -ve to ground?. And how to identify the +ve and -ve terminals of the CR2032. I tried doing it by checking the connectivity using a multimeter, however, I am not able to figure out what connections to make if I need to use the battery.

Sorry, If my questions are too lame. But any advise and support regarding this will be helpful before I do the hardware connections. I have simulated it in Proteus as shown in the image below enter image description here


1 Answer 1

  1. for genaral purpose storing the state or result that will be remembered when mcu is powered off.
  2. For storing parameters that are seldom or never changed, you have to write some protection routine in MCU for make sure that you don't write in EEPROM too frequently, because the EEPROM has final number of WR cycles.
  3. Yes you need to remove diodes or circuits that may charge the CR2032 else it will explode. https://www.fabtolab.com/RTC-DS1307 find the remark about using non rechargable battery if this is the same module.
  4. Who can know that on your behalf? Nobody.
  • \$\begingroup\$ For the 2nd one, what kind of parameters?, you mean parameters related to the RTC or its a stand alone EEPROM chip that can be used separately to store any long term data?. And for the 4 th one, I presumed someone who has used the same module may know it. Between, I had also asked on how to identify the +ve and -ve terminals of the battery on this module? \$\endgroup\$
    – PsychedGuy
    Dec 6, 2015 at 23:54
  • \$\begingroup\$ Any ways, I finally figured out the connections. It would be great if you can clarify my doubt regarding the eeprom I have mentioned in my previous comment. Thanks! \$\endgroup\$
    – PsychedGuy
    Dec 7, 2015 at 4:17
  • 1
    \$\begingroup\$ On that board you have rtc and eeprom chip, the rtc chip has 56 bytes NVRAM for general purpose use, the other built in ram is used for rtc (time,date,..). You store in the eeprom any kind of values (nothing related to rtc), I named them parameters because you need to flash them in eeprom, they are more static variables, that's all. \$\endgroup\$ Dec 7, 2015 at 19:52

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